From owner-freebsd-hackers Fri Nov 28 22:55:43 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id WAA10607 for hackers-outgoing; Fri, 28 Nov 1997 22:55:43 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from freebie.lemis.com (gregl1.lnk.telstra.net [139.130.136.133]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id WAA10602 for ; Fri, 28 Nov 1997 22:55:38 -0800 (PST) (envelope-from grog@lemis.com) Received: (from grog@localhost) by freebie.lemis.com (8.8.8/8.8.7) id RAA27918; Sat, 29 Nov 1997 17:25:27 +1030 (CST) (envelope-from grog) Message-ID: <19971129172526.39614@lemis.com> Date: Sat, 29 Nov 1997 17:25:26 +1030 From: Greg Lehey To: David Dawes Cc: hackers@FreeBSD.ORG Subject: Re: Drive Mirroring References: <199711290422.PAA23032@mother.sneaker.net.au> <19971129151057.57891@lemis.com> <19971129165905.08819@rf900.physics.usyd.edu.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.84e In-Reply-To: <19971129165905.08819@rf900.physics.usyd.edu.au>; from David Dawes on Sat, Nov 29, 1997 at 04:59:05PM +1100 Organisation: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 WWW-Home-Page: http://www.lemis.com/~grog Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk On Sat, Nov 29, 1997 at 04:59:05PM +1100, David Dawes wrote: > On Sat, Nov 29, 1997 at 03:10:57PM +1030, Greg Lehey wrote: >> On Sat, Nov 29, 1997 at 03:22:12PM +1100, Andrew Kenneth Milton wrote: >>>> Would a software RAID implementation be able to cope with having a drive >>>> removed? >>> >>> The last implementation I saw of software RAID on Solaris didn't >>> (about two years ago). >>> >>> It wouldn't boot from the secondary drives, >> >> Booting is a different matter. It's a lot more complicated, since you >> need to explain RAID to the bootstrap. I don't think that's >> feasible. But once the system is up and running, all other file >> systems should be able to be RAID. > > The Veritas software that Sun supplies with their Sparc storage arrays > these days does allow this. It was one of the first things I tried > (having a mirrored boot disk, removing the one it usually boots from, > and booting from the other). In the configuration I tested, the boot > disk and its mirror were both "normal" disks attached to the primary > scsi controller, and not disks in the storage arrays. Mirroring is the > only RAID type supported for boot disks though. Yes, Tandem supplies Veritas as well, and Version 2 (which is even more convoluted than Version 1) supports booting from a Veritas volume. It does this by imposing significant restrictions on the format of root volumes. It's not nice--I'd guess that it would make more sense to have a really intelligent boot to handle things until Veritas (or whatever) was up and running. For the benefit of those who don't know Veritas: it runs as a number of processes, notably the Volume Daemon. Until that's up and running, you can't mount Veritas volumes (virtual disks). Greg